The subject invention relates to an automatic chemical anaylzer, and more particularly to an automatic chemical analyzer capable of changing from one reagent to another in the same channel.
Apparatus for continuously and automatically analyzing liquid samples such as blood, urine, etc. are presently available and are being used extensively in the clinical and chemical fields. In the larger type of apparatus in which many channels are provided, different analyses of the same sample can be carried out simultaneously. (See, for example my U.S. Pat. No. 3,881,872 entitled "Automatic Analyzing Apparatus.") However, in the more compact small-sized apparatus, a lesser number of channels, sometimes only a single channel, are provided. (See my application Ser. No. 666,921, filed Mar. 15, 1976, now U.S. Pat. No. 4,090,848.) If, for example, only one channel is provided and it is intended to carry out more than one type of analysis of a given sample, various operations such as selecting the measuring wavelength, washing the flow-through system, changing over the reagent, selecting the desired analyzing method, etc. will be necessary. Of these operations, reagent changeover is the most troublesome. This is because there is only one pump for a plurality of reagents housed in separate storage tanks, selection of one particular reagent or another being determined by a valve located between said tanks and said pump. In other words, after a given reagent has been force-fed into the reaction chamber through the action of the pump, it is necessary to wash not only the valve and associated feed lines connected to the reaction vessel but the pump also, before the next reagent can be sent to the reaction vessel. This indeed is very time consuming. Moreover, since the pump is difficult to clean, the chances of traces of the previous reagent remaining are likely so that when the next reagent is passed through, cross-contamination is a possibility. Another drawback with this arrangement is that reagent consumption is uneconomical, since it is necessary to displace reagent in a sufficient amount to reach the pump interior for each analysis.
One object of this invention is to provide an automatic chemical analyzer capable of shortening the washing time when changing over from one type of analysis to another.
Another object of this invention is to provide an automatic chemical analyzer capable of carrying out sampling without the adverse effect of cross-contamination.
A further object of this invention is to provide an automatic chemical analyzer capable of economic reagent utilization.